Mr Carr, who died at his home near Malaga in Spain, was diagnosed with inoperable lung cancer in the summer.

Friends said it was possible that the years he spent curing smokers in smoke-filled sessions at his clinics might have contributed to the illness, although it might also be linked to his previous heavy smoking.

Price worth paying

Mr Carr himself was convinced he would have died many years earlier if he had not kicked the smoking habit.

He said: "Given that I am informed that I have cured at least 10 million smokers on a conservative estimation, even if that is the case, it's a price worth paying."

He gave up accountancy to set up his first clinic in south-west London in 1983.

He has since set up 70 clinics in 30 countries, treating 45,000 people last year.

His first book, Allen Carr's Easyway To Stop Smoking, has sold more than seven million copies.

Celebrities to have benefited from Mr Carr's methods include Sir Anthony Hopkins and Sir Richard Branson.

John Dicey, worldwide director of Allen Carr's Easyway, said: "The fact that a former 100-a-day smoker, having quit in his middle age, lived to the ripe old age of 72 is a tremendous message to all smokers.

"Allen Carr's refreshingly different approach to stopping smoking earned him the position as the world's leading expert on helping smokers to quit."